Juneau's hydropower at a glance

Juneau relies on hydropower from four plants, particularly the Snettisham Hydroelectric Project, which supplies most of the town's electricity.

The adequacy of Juneau's hydropower plants is measured partly by whether there's enough electricity to go around at a given moment. For example, Juneau households may demand more electricity on one cold winter evening than at any other time of the year. Local power plants have to meet demand at that moment, which is called peaking.

Juneau never has had a peaking problem, said David Stone, spokesman for Alaska Electric Light & Power, Juneau's privately owned utility. Juneau's hydro plants can produce up to 85 megawatts of power on demand, and the town's highest peak ever came in January 1996, when customers demanded 65 megawatts, he said. Sixty-five megawatts is the equivalent of 650,000 100-watt light bulbs turned on at once.

"You can see there's plenty of room for peaking without us having to revert to diesel" generators, said Stone, adding the utility owns three diesel plants capable of producing 91.5 megawatts of backup power.

Another way to measure adequacy of the hydro plants is by whether there's enough electricity to go around in a given year.

In Juneau, the amount of hydropower available annually largely depends on how much water is in Long Lake and Crater Lake, used to generate electricity at Snettisham. Juneau also draws hydropower from three smaller facilities.

In dry years, the hydro plants can reliably supply 323 million kilowatt hours of electricity annually - usually enough to meet demand from AEL&P's 14,500 customers, who used a total of 302 million kilowatt hours in 2000, Stone said. An average household uses about 10,090 kilowatt hours annually.

In average-water years, the plants can supply about 378 million kilowatt hours, he said. If AEL&P builds a proposed hydro facility at Lake Dorothy near Taku Inlet, the two-phase project initially would supply another 80 million kilowatt hours annually and eventually an extra 187 million kilowatt hours each year.

AEL&P owns all of Juneau's hydropower plants but Snettisham, the largest:

Snettisham Hydroelectric Project: Snettisham generates 80 to 85 percent of Juneau's electric power. The state-owned plant draws water from Long Lake and Crater Lake, capable of producing 325 million kilowatt hours in an average-water year. The Long Lake unit came online in 1973 and Crater Lake in 1990. The facility is about 30 miles southeast of Juneau.

Annex Creek Hydro Project: Annex Creek generates about 10 percent of Juneau's electric power. The plant draws water from Annex Creek Lake, capable of producing 27 million kilowatt hours in an average-water year. Annex Creek was built in 1915. The facility is about 15 miles from Thane up Taku Inlet.

Salmon Creek Dam and Powerhouses: Salmon Creek Dam generates about 10 percent of Juneau's electric power. The plant is capable of producing 26 million kilowatt hours in an average-water year. Salmon Creek Dam came online in 1914 in a high valley three miles above Bartlett Regional Hospital. The facility also supplies drinking water to Juneau.

Gold Creek Hydro Plant: Gold Creek generates roughly 2 percent of Juneau's electric power. Gold Creek is a run-of-the-river facility, meaning its power output depends on the flow of the creek. Power production drops off almost completely in winter when the creek freezes. Gold Creek is capable of producing 5 million kilowatt hours of electricity annually, but its contribution is not counted when the utility measures annual energy capacity, Stone said. The current plant was built in 1914 and upgraded in the early 1950s. It's downtown behind the Federal Building.

Most of the power plants and the utility itself date to Juneau's gold rush in the late 1800s and early 1900s. Snettisham is a notable exception; it came online in 1973 and was expanded in 1990.

Originally a federal project, Snettisham was purchased by the state in 1998 for $100 million. The state has a contract with AEL&P allowing the utility to sell electricity generated at Snettisham. In exchange, AEL&P has to maintain the plant and pay off 35-year bonds issued by the state when it bought Snettisham from the federal government. When the bonds mature and the utility is free of the debt, it plans to lower electrical rates for consumers, unless the state says otherwise, Stone said.

In the meantime, Snettisham could transfer to AEL&P. As part of its deal with the state, AEL&P has an exclusive option to purchase Snettisham in 2003. However, the company is not inclined to buy the plant, said Stone, noting it may not be in the best interests of consumers.

"It could translate into higher rates ... the state does not have to have a Federal Energy Regulatory Commission license, it does not have to pay the Forest Service money for the right of way, it doesn't have to pay city property tax," said Stone, adding the utility would have to assume those costs and ultimately consumers would pay more.